This usually happens when you check for null for class variable.
Solution: copy class variable to local variable.
class PinActivity : AppCompatActivity() { private var mapFragment: SupportMapFragment? = null fun loadMap() { // Smart cast to 'SupportMapFragment!' is impossible, because 'mapFragment' is a mutable property that could have been changed by this time /* if (mapFragment == null) { } */ // copy class variable to local variable var localMapFragment = this.mapFragment if (localMapFragment == null) { localMapFragment = SupportMapFragment.newInstance() ... } else { ... } ... this.mapFragment = localMaFragment }}Or use safe calls.
mapFragment?.also { // do something}